"We are particularly concerned over the inflow of [human] migration into the areas the pipeline would cross," said Roberto Smeraldi, director of the Brazil branch of the advocacy group Friends of the Earth.

"The process of colonization will bring environmental problems into new frontiers. This all implies deforestation and occupation of this land—an explosive situation."

"This pipeline will unleash major environmental, cultural, and social impacts on the Amazon rain forest and on local populations," Soltani said.

She said the project promises big damage "over the next 20 or 30 years, as new offshoots of the pipeline could fuel and enable energy-intensive industries to expand in relatively pristine and ecologically fragile areas of the Amazon rain forest."

Not Sustainable?

Some industry studies have shown that shipping natural gas via pipeline ceases to be profitable at distances greater than 1,865 miles (3,000 kilometers)—proof, opponents say, that the plan is not a sound energy strategy.

Smeraldi, of Friends of the Earth, said the plan is purely political and that the Chavez government has failed to show whether its gas reserves are even sustainable.

"They don't have an economic feasibility study, and Venezuela so far has never made public any estimates about the size and the likely duration of the gas reserves," he said.

"How do you convince an investor to put money into something without that information?"

In November Marcio Zimmermann, secretary for energy planning at Brazil's Ministry of Mines and Energy, was quoted by Brazilian media saying that the pipeline may only extend to the north of Brazil until Venezuela assures involved parties that its gas supply is sufficient to continue southward.

"First we studied the plan in its entirety," Zimmermann said, "and now we are studying the possibility to doing it in stages based on the availability of Venezuelan gas."